You need to ensure that throughout the transaction the data maintains the original version

You are developing a database application by using Microsoft SQL Server 2012.
An application that uses a database begins to run slowly.
You discover that during reads, the transaction experiences blocking from concurrent
updates.
You need to ensure that throughout the transaction the data maintains the original version.
What should you do?

A.
Add a HASH hint to the query.

B.
Add a LOOP hint to the query.

C.
Add a FORCESEEK hint to the query.

D.
Add an INCLUDE clause to the index.

E.
Add a FORCESCAN hint to the Attach query.

F.
Add a columnstore index to cover the query.

G.
Enable the optimize for ad hoc workloads option.

H.
Cover the unique clustered index with a columnstore index.

I.
Include a SET FORCEPLAN ON statement before you run the query.

J.
Include a SET STATISTICS PROFILE ON statement before you run the query.
K.
Include a SET STATISTICS SHOWPLAN_XML ON statement before you run the query.
L.
Include a SET TRANSACTION ISOLATION LEVEL REPEATABLE READ statement
before you run the query.
M.
Include a SET TRANSACTION ISOLATION LEVEL SNAPSHOT statement before you
run the query.
N.
Include a SET TRANSACTION ISOLATION LEVEL SERIALIZABLE statement before you
run the query.