At December $31,2022,$ Mongo, Inc. reported in its balance sheet a net loss of $$3$ million related to its pension plan. The actuary for Mongo at the end of $2023$ increased her estimate of future salary levels. Mongo's entry to record the effect of this change will include:

$$ a$)$ A debit to loss$-$OCI and a credit to PBO.

b$)$ A debit to PBO and a credit to loss$-$OCI.

c$)$ A debit to pension expense and a credit to PBO.

d$)$ A debit to pension expense and a credit to loss$-$OCL.