For the past (A)few years, researchers (B)have perfecting (C)their control over the movements of cells and microbes by (D)using low-power laser beam. (E)No error.

For the past (A)few years, researchers (B)have perfecting (C)their control over the movements of cells and microbes by (D)using low-power laser beam. (E)No error.

A (A)

B (B)

C (C)

D (D)

Solution

Correct Answer: Option B