Question

while initial surveys of the calder ridge fault focused on surface fractures, later studies examined subsurface stress patterns in greater detail. engineers warned in 1998 that minor tremors ___ larger structural shifts if monitoring systems were not updated. that concern led to the installation of new sensors across a 12 - kilometer section of the ridge.
20
which choice completes the text so that it conforms to the conventions of standard english?
a cause
b caused
c have caused
d would cause

Explanation:

The sentence is in the past (engineers warned in 1998) and describes a conditional situation (if monitoring systems were not updated) about a future - in - the - past event. The structure “warned that... if... were not...” indicates a hypothetical situation in the past, so we need a verb form that shows a future - in - the - past action. “would cause” is used to express a conditional result in the past, which fits the context. “cause” is present tense, “caused” is simple past (doesn't fit the conditional future - in - past context), and “have caused” is present perfect (also doesn't fit the context of the past warning about a conditional future event).

Answer:

D. would cause