Top Law Schools

Guys,
Can anyone explain to me why the answer is A? I thought tenants in common can either voluntarily and involuntarily partition the land?
The question is from the NCBE website.

Two sisters own a single tract of land as tenants in common each holding one half interest. The younger sister entered into 3year written lease
with a tenant; the lease described by metes and bounds a specified portion of the land, which consisted of about 40% of the total tract. The tenant went into sole possession of the leased portion of the land. The older sister has sued both the younger sister and the tenant to establish the older sister's right of possession on the leased portion of the land.

Who is likely to prevail?
a) the older sister, bc the younger sister cannot unilaterally partition the land without the older sister's consent
b) the older sister, bc the younger sister may not lease her undivided interest in the land without the older sister's consent
c) the younger sister and the tenant, bc the older sister has been excluded only from the specified portion of the land subject to the lease, which makes up less than 1/2 of the land's total area
d) the younger sister and the tenant, because the younger sister's lease to the tenant was necessarily for less than a fee simple interest

You're correct that as a tenant in common, the younger sister had the right to lease her interest. But the issue here is that the tenant was claiming sole possession of the 40%. Instead, both the older sister and the tenant would have the right to the entirety of the property since the younger sister and the tenant could not partition the property as they tried to do here without the consent of the older sister, the other tenant in common.

Sean (Silverman Bar Exam Tutoring)