Which of the following commodities is a good?

a.

a swimming lesson

b.

a desk

c.

house cleaning

d.

dog walking

Goods are tangible, they can be seen or felt. the only tangible thing here is the desk. all the others are services.

B) A desk

Explanation:

In an economy, consumers can buy goods and services. Goods are characterized by their material (tangible) property, such as a table, a shoe, a food, and anything that has physical property. Services are all we can buy but don't have a material property, (intangibles). For example, a swimming class, cleaning a residence, a walk.

-- Start a list.
-- At the beginning of the list, write zero. 
-- Next on the list, write ' 1 '.
-- Now you have the beginning of the Fibonacci series.
-- Whenever you want to add a new term to the list, sum up
     the last two terms on the list.  Their sum is the new term.