Question

which is the best way to complete the text? carmen was an experienced speed chess player, but still struggled with the pace of competitive tournaments. player but player; but player, but

Explanation:

The first part "Carmen was an experienced speed - chess player" is an independent clause. The second part "still struggled with the pace of competitive tournaments" is also an independent clause. A comma is used to separate two independent clauses when a coordinating conjunction like "but" is used to connect them. A semicolon is not appropriate here as it is used mainly to connect two closely related independent clauses without a coordinating conjunction. And no punctuation between "player" and "but" makes the sentence structure incorrect.

Answer:

player, but