Answer:
Assuming Shanna rented the property for a business purpose, then:
A) Shanna can deduct $8,400 for rent expense in 2018.
B) If the rent paid is for 24 months, then Shanna can only deduct 9 months worth of rent for 2018 = ($8,400 / 24) x 9 = $350 x 9 = $3,150