In the following passage some words have been deleted. Fill in the blanks with the help of the alternatives given. Select the most appropriate option for each blank.
Sanitation refers to public health conditions___ (1)__ to clean drinking water and adequate treatment and disposal __(2)____ human waste and sewage.  ___(3)___ human contact with faeces is part of sanitation. Sanitation system ___(4)___ to protect human health by providing a clean environment  __(5)___ will stop the transmission of disease.

Q:

Select the most appropriate option for blank No. 5.

• 1
  that
• 2
  who
• 3
  whom
• 4
  these