Combine the following sentences using a subordinate conjunction.
Esther observed the joyous look in Josh's eyes. She whirled around to look up the hill.
A. Esther observed the joyous look in Josh's eyes, and she whirled around to look up the hill.
B. Esther observed the joyous look in Josh's eyes; she whirled around to look up the hill.
C. When Esther observed the joyous look in Josh's eyes, she whirled around to look up the hill.
C is the correct answer, because it is the only option where a subordinate conjunction is used - 'when'. In A, 'and' is a coordinate conjunction, not subordinate. And in B there is no conjunction at all.
