Question

use the drop - down menus to select the best answers. watson and crick <> discovered the structure of dna. <> developed the technique of cell culturing. <> was the first researcher to isolate individual components of cells.

Explanation:

First Dropdown (Watson and Crick):

Watson and Crick are known for discovering the double - helix structure of DNA. So the correct action for them is "discovered the structure of DNA".

Second Dropdown (developed the technique of cell culturing):

The technique of cell culturing was developed by Alexis Carrel. But among common options, if we consider, for example, George Otto Gey developed the HeLa cell culture technique, but in general, for the first part of the second sentence (the one about developing cell culturing), a key figure is Alexis Carrel (though the options might have specific ones, but based on knowledge, the action "developed the technique of cell culturing" is associated with researchers like Alexis Carrel. However, if we assume the options are standard, the correct match for developing cell culturing is a researcher like Alexis Carrel (but since the problem has dropdowns, we need to pick the correct option from the dropdown. But based on the given text, the first blank for Watson and Crick is "discovered the structure of DNA". For the second blank (developed the technique of cell culturing), a possible answer is a researcher like Alexis Carrel (but if we follow the problem's dropdowns, we select the appropriate option. For the third blank (was the first researcher to isolate individual components of cells), that is related to researchers like Claude (who used centrifugation to isolate cell components). But let's focus on the first two blanks as per the visible text.

Answer:

First dropdown (Watson and Crick): discovered the structure of DNA
Second dropdown (developed the technique of cell culturing): [The appropriate researcher from dropdown, e.g., if options include Alexis Carrel, then that]
Third dropdown (was the first researcher to isolate individual components of cells): [The appropriate researcher from dropdown, e.g., Claude]

(Note: Since the actual dropdown options are not fully visible, but based on biological knowledge, Watson and Crick discovered DNA structure, cell culturing was developed by Alexis Carrel (or related), and isolating cell components was done by Claude (or related).)